1. Field of the Invention
This invention relates to a leathery sheet material and to a process for the preparation thereof. More particularly, this invention is concerned with a leathery sheet material having excellent flexibility, antistatic properties and soil resistance which comprises a fibrous mat and a specific polyurethane composition applied all over the mat, and with a process for producing the same.
2. Description of the Prior Art
Heretofore, it has been known to produce artificial leathers consisting mainly of a non-woven, woven, or knitted fabric and a polyurethane composition as a substitute for natural leather. These artificial leathers, however, have the disadvantages: These artificial leathers tend to be charged with static electricity, and accordingly be contaminated with adsorbed dust; These artificial leathers do not have adequate flexibility suited for footwear and clothing uses.
In order to overcome the above-mentioned disadvantages of the prior arts, it has been proposed to produce artificial leathers by using a polyurethane composition containing a third component.
For example, Japanese Patent Application Publication No. 20522/77, Fukushima et al, published June 4, 1977, discloses a process for the preparation of artificial leathers using a polyurethane composition which contains as a third component a carboxylic acid, carboxylic acid ester, nitrile, amide, amine, sulfonic acid ester, ureido or urethane having an alkyl group of 4 to 50 carbon atoms. According to this process, a leathery sheet material having good flexibility is obtained, because the third component prevents the adhesion between fibers and polyurethane. As for the third components, there are exemplified stearic acid, sorbitanmonostearate, stearylonitrile, stearic acid amide, cetylamine, octadecane sulfonic acid methyl ester, stearic acid monoureido, ethyl cellulose and octadecyl urethane. However, the obtained leathery sheet material does not have antistatic properties when these compounds are used.
Japanese Patent Application Laid-Open No. 45654/77, Onoda et al, published Apr. 11, 1977, discloses a polyurethane composition containing a dicarboxylic acid ester so as to improve antistatic properties of the polyurethane. As for the dicarboxylic acid esters, there are exemplified compounds obtained by reacting itaconic acid, adipic acid or succinic acid with an adduct of actyl alcohol or lauryl alcohol and ethylene oxide. However, since the compounds are poor in compatibility with a polyurethane, they tend to bleed on the surface of artificial leathers in a long period and accordingly contaminate the articles. Further, the obtained artificial leathers are not endowed with durable antistatic properties.